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Number Bases

Back in Chapter 9, we got a look at octal (base 8) and hexadecimal (base 16) numbers. In arithmetic expressions, the shell supports integer constants in any base.

Table 34-2: Specifying Different Number Bases

Notation Description

Notation Description

number By default, numbers without any notation are treated as decimal (base 10) integers.

0number In arithmetic expressions, numbers with a leading zero are considered octal.

0xnumber Hexadecimal notation

base#number number is in base

Some examples:

[me@linuxbox ~]$ echo $((0xff))

255

[me@linuxbox ~]$ echo $((2#11111111))

255

[me@linuxbox ~]$ echo $((0xff))

255

[me@linuxbox ~]$ echo $((2#11111111))

255

In the examples above, we print the value of the hexadecimal number ff (the largest two-digit number) and the largest eight-digit binary (base 2) number.

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